Tool



.12,19 6. .J. p. CATLIN ETAL .2,39

Patented Feb. 12, 1946 v TOOL John P. Catlin, Fairfield, George B. Eckstein,

Bridgeport, and Milton B.`

Vordahl, Fairfield,

Conn., assignors to Remington Arms Company, Inc., Bridgeport, Conn., acorporation of Delaware Application December 26, 1942,`Serial N 0. 470,172

1 Claim.

This invention relates to an improved means for making metallic tubular articles: IVioreover, while not limited to such use, it is especiallyaclapted for making metallic cartridge cases.

An object of the invention is to provide ammunition components of improved quality and strength. A` further object is to-forma cartridge case which will be free from base failures 'on firing. A still further object is to provide an improved punch for preventing the formation of cold shuts in the heading of a cartridge case.

Other objects, features and advantages 'of the invention will be disclosed in the following description of one embodiment of the invention. It will be understood, however, that the device shown and described is for the purpose of illustration only and. that the invention is not limited thereto but includes all modiiications threof Within the scope of the appended claim.

In the drawing: r

Fig. 1 is a fragmentary elevation partly in section of a suitable die and hunter including the improved punch of this invention.

Fig. 2 is an enlarged fragmentary sectional view Of the active portion of one form of punch.

Fig. 3 is an enlarged fragmentary sectional View Of another form of punch.

Pig. 4: is an enlarged fragmentary sectional view Of a third form of punch.

Fig. 5 is a reproduction of a phtograph of a Sectioned and etched Shell prior to heading Showing its rnetallographio Structure.

Fig. 6 is a reproduction of a photograph of a sectioned and etched Shell after the engagement of the head thereof by the heading hunter and before the interior of the head -has contacted the heading punch. V

Fig. 'I is a reproduction of a photograph of a sectioned and etched shell which is fully beaded.

Fig. 8 is an enlargediragmentary sectional view of the active portion of a fourth form, of punch.

A. not infrequently occurring detect in cartridge cases has been bsefailureori iiring, and, vvhereas this clefect is encountered only' to a relatively small estent in brass Cases, its occurrence in cases of harder r'netals, such as steel, has been so persistent as to render the manufacture of steel cases by present methods impracticable. V

Briefly, ammunition components, such as cartridge cases, h.ave been manufactured almost exclusively by blanking out ay disk from a sheet of suitable metal, such as brass, gilding metal, or steel and then subjecting the disk to successive cupping and drawing operations, which may include heat treatments between successive draws, until the blank assumes the shape of a substantially Cylindrical tube having a closed dome-Shaped end. The persistence of the dome throughout successive draws may be attributed to the fact that some pivoting action occurs between the punch and the walls of the partially formed cup; and further to the fact that radial compressive stresses are exerted by the die which tend to decrease the radius of the arc formed at the base of the cup, thus promoting the formation of the dome. Such dome must be exteriorly completely flattened or. "bumped, a pocket formed in the exteriorly flat head to receive the primer, and a. flash hole opened between the prirner pocket and the shell interior.

The existence of the dome-shape base is somewhat advantageous in that it keeps metal in the head of the draw piece and is associated with good wall concentricity but it has a distinctly unfavorable effect during the subsequent bumping and. pocketing operation, in that the dome increases the tendency of the metal surface to interiorly fold upon itself or "gather' when subjected to the compressive stresses. These folds or gatherings in the metal are terrned "cold shuts" and their formation develops paths of shear which are a chief source of head failures.

Although both the hard and soft metals are susceptible to doming during cupping and. drawing, the tendency to form cold shuts 'during bumping appears to be less in soft metals, such as brass, than it is in the harder ferrous metals.

This maybe ascribed to the different strength characteristics of the two metals, and, more particularly, to the characteristic yield point elongatien of annealed or normalized low carbon steels which give the familiar "jog" during tensile testing, -whereas brass gives a substantially Smooth unloroken stress strain curve. Thus, in heading a brass case, presumably the progressive work hardening suffered during bumping distributes the flow of metal sufftciently so that the tendency toward cold shut formation is largely obviated. On the other hand, steel's characteristics local yielding does not tend to promote the flow of metal and hence predisposes to cold shut formatien, and it becomes imperative to control the metal now in bumping and pocketing operations to overcome this.

The present invention comprises the development 'of a punch of ilow controlling contour aclapted to be used during the heading operation and which entirely eliminates the formation of cold shuts in the beads Of steel cases.

The machine parts, which perform the heading operation, are diagrammatically illustrated in Fig. 1. The shell 9, as produced with a domed head by drawing, is placed in a die 111 upon a heading punch 11. The drawing operations result in a shell having a wall thickness which increases toward the head and the heading punch is of such dimensions as to engage the interior of the shell in substantially the manner shown in Fig. 1, an empty space remaining between the end of the punch and the interior of the head.

For the purpose of this specification, t may be considered that the punch 11 is fixed relative to the die 10. The Shell thus supported is beaded by applying thereto the heading bunter 12, the end of which is provided with a centrally disposed projection or teat 13 which forms the primer pocket 14 (F'g. 7). A small portion of the metal displaced in the formation of the primer pocket flows outward to form the exteriorly ilat head and a slightly projecting rim 15. The greater portion, however, is displaced inwardly, and the present invention is concerned with the disposition of this inwardly displaced metal in such a manner as to form a finished head, all parts Of which are of sound metal and free from cold shuts.

The metallographic structure of the drawn r piece is shown in Fig. 5. The rollin and subsequent drawing of the metal has produced flow lines which extend longitudinally of the body and continue therefrorn across the head.in a line substantially parallel to the exterior surface of the dome. The initial displacement of the metal of the head when unsupported on the inside and struck on the outside by the hunter 12 and the resultine structure, are shown in Fig. 6. It will be seen that the curve of the central portion of the dome has been reversed, but the flow lines remain substantially continuous. The interior surface of the head presents a convex arc 16, and the flow lines of the metal adjacent this arc are substantially parallel thereto. At the junotion of this arc and the substantially undisplaced metal 17 of the draw piece, the curvature is sharply reversed presenting an annulus 18 of maximum curvature opposite which the flow lines of the metal have a corresponding curvature. The head thus displaced is about to be engaged by a heading punch. 7 In prior practice, the end Of the heading punch has been made flat to provide a solid anvil support for the metal which the teat 13 of the heading bunter. It will be apparent, however, that if a flat surface is presented to the arc 16 of the interior head surface as shown in Fig. 6, it will engage the midportion only of such surface, leaving a pocket at the annular portion 18. Consequently, if the heading bunter is advanced further, the metal coniined between the fiat end of the punch and. the heading bunter will tend to flow outwardly into such pocket and to form creases therein which, in the final movement of the heading bunter, will be completely closed forming hazardous cold shuts. The present inVention conternplates a punch having an end contoured to engage the interior head of the case to enable and enhance the natural flow Of the metal thereof. The punch is designed to conform substantially to the arcuate interior configuration of the head, and, more particularly, to the curvature thereof at the annulus 18 of maximum ourvature, as shown in Fig.

is being displaced by 6, which iigure, it will be recalled, is a reproduction of an actual photograph of the head after initial displacement by the heading punch and before any contact has been made With the punch.

Re ferring to the punch shown in F'ig. l, it will be seen that the lower end of the punch has a smooth rounded bevel as at 19, the slope and contour of the bevel corresponding substantially to the interior undisplaced wall portion 17 of the head when deformed, as in Fig. 6.

F'urthermore, the end of the punch is dished or countersunk so as to afford a recess .20 adapted to accommodate the interior configuration or arc 16 of the head. In Figs. 2, 3 and 1, the surface of the recess 213 is shaped expeditiousl like a truncated cone, the sloping walls Of which are substantially tangent to the convex surface 16, thus providing for the flow of metal away from the pocketed region 18 as hereinafter described. It will be clear, however, that the specific shape of the recess 20 may conform more closely to the curvature of the arc 16 and as shown in Fig. 8 may be made substantially arcuate.

The jurrcture of the outer extrernities of the recess 2il and the lower end of the bevel 19 cornprises an annular smoothly rounded shoulder portion 21, the radiu` of curvature of which is carefully dimensioned by grinding and lapping to conform to the maximum curvature of the head at the annular pocket 18.

As a result, it will be clear that on further displacement of the metal by the heading hunter, the interior metal of the head at the annulus 18 of maximum curvature is first engaged by the shoulder portion 21 of the punch so that the ad- .iacent metal of the head is prevented from flowing into the pocket 18 and, in effect, is caused to flow away from the pockets by reason of the recess.20 and the bevel 19 thus reversing the direction of flow Of metal which otherwise would form cold shuts.

The major benefits of the invention would be secured by a punch having a contoured end cornprising simply the beveled enol E9, the rounded Shoulder 21 and a truncated or arcuate recess Zi! as described above and shown in Figs. 4 and 8 respectively. However, the maintenance of the W lines produced by drawing with' a minimum of distortion, as distinguished from the production of folds, may be further enhanced by deepening the central portion of recess 28.

The punch shown in Fig. 3 is a modiiication of the punch shown in Fig. l and embodies a relatively shallow aperture 22 concentric with the recess 20. Thus, the metal which has been crowded directly forward by the pocket forming teat 13 of the heading bunter 12 is enabled to flow inwardly substantially freely from the recess 20 toward and into the aperture 22, insuring the maintenance of undistorted flow lines.

A further modification Of the punch is shown in Fig. 2, in which there is provided a central substantially cylindrical aperture or well 23 of considerable depth into which the head metal displaced by bunter teat 24 flows directly and without obstruction while the flow Of the surrounding metal is confined and guicled by shoulder 21 and the surface of recess 20. The use of a punch of this (Fig. 2) type results in the beaded shell shown in Fig. 7, the interior coniiguration conforming to that of the end portion Of the punch except that the deep punch recess or well 23 has not been entirely filled. Projection 24, formed within the recess 23 and subsequently removed in theoperation of piercing the flash hole, is excas metal accumulated while directing the metal flow as described to produce the lnal configuration and metallographic structure illustrated.

It is thus seen that by providing a support 2l which prevents the llow Of metal toward theregion la Of potential folding and providing a clearance for ilowing the metal inwardly away from such region of potential folding, the invention accomplishes its object of providing a headed shell entirely free from folds and cold shuts.

What is claimed is:

In apparatus for the heading of drawn steel cartridge shells which are exteriorly domed and. interiorly comprise a concave head surface joined to an interior slightly tapered side wall by an annular fillet extending from a base junction' with said concave head to said side Wall; a Shell receiving die a hunter comprising a centrally disposed pocket forming teat adapted to engage and inwardly displace the head metal of a shell held in said die; and a punch' for holding a shell in said die in position to be operated on by said hunter, said punch being slightly tapered to grin the interior slightly tapered side wall of said shell while spaced from said fillet and said concave head and. comprising a smooth, rounded, beveled, exterior surface substantially conforming t the configuration of and adapted for engagement by said fillet after an initial inward displacementof the head metal by said hunter, said beveled puhch surface terrninating in a shoulder adapted after such initial displacement of the head metal to engage the head in the region of the base of said fillet to prevent the ilow of metal into this region, the end portion of said punch within said shoulder being formed to a center recess having .a Smooth continuous conical surface, the base of which iS blended into the shoulder to direct the flow of metal radially inward from the base of said iillet and thereby prevent the formation of cold. shuts. 4

.IOI-IN P. OATLIN'.

GEORGE R. ECKSTEIN.

MIIJTON 13. VORDAHL. 

